This invention relates to an apparatus for lifting a group of vertically oriented stacks of battery plates out of a stacking apparatus and placing them at the proper spacing and rotational orientation in a cast on fixture.
In the manufacture of wet cell storage batteries, alternate plates are encapsulated in microporous envelopes and pairs of encapsulated and bare plates are assembled into stacks, with each stack forming one cell of a battery. The plates have lugs projecting from their upper edges that are offset from the vertical center line of the plates. The plates in every other cell in a battery are rotated 180.degree. with respect to the plates in adjacent cells so that the lugs in alternate cells are offset from one another. The lugs on the plates in each cell are interconnected by casting an electrically conductive strip onto them. The groups of plates for a battery are assembled in this alternating cell "battery configuration" in a "cast on" fixture, which supports the plates in the proper orientation while the straps are cast on them.
The process of encapsulating the plates, assembling them into stacks that will constitute a cell and placing the stacks in the cast on fixture in battery configuration has to a large degree become automated over the last several years. Johnson, U.S. Pat. No. 4,407,063, discloses an apparatus for encapsulating plates, and a later version of this apparatus combines encapsulated plates with noncapsulated plates in horizontally oriented pairs. Johnson et al., U.S. Pat. No. 4,824,307, discloses an apparatus that assembles the pairs and places them in vertically oriented stacks, each of which contains the proper number of plates to form a cell, and then transports the stacks to the cast on fixture. In addition, Tekmax Inc. of Tangent, Oreg., the assignee of Johnson, '063 and Johnson et al., '307, has produced and sold at least one plate handling apparatus that lifts the stacks out of the stacking apparatus and places them in the cast on fixture.
However, the separation between the stacks of plates in the stacking apparatus is greater than in battery configuration, and the prior art Tekmax handling apparatus cannot reduce the separation between the stacks of plates while they are being gripped by the apparatus. In addition, the prior art Tekmax handling apparatus cannot rotate alternate groups of plates to place them in battery configuration. Thus, hand manipulation is necessary after the stacks are placed in the cast on fixture. Another difficulty with the prior art Tekmax handling apparatus is that the fixture must be aligned with the handling apparatus which, due to space constraints, may not be desirable. Furthermore, the gripping heads on the prior art Tekmax apparatus have paired fingers that are moved together to grip a stack of plates and apart to release the stack by a parallelogram linkage that is activated by a pneumatic actuator. Thus, the fingers necessarily open and close at the same speed and with the same amount of force. As a result, a long stroke, high force actuator is necessary to achieve both the fast opening required for clean release of the stack and the high gripping force required to grip the stack and lift it. In addition, a parallelogram linkage is expensive to fabricate and maintain. Finally, with a parallelogram linkage, if cylinder pressure is lost the plates will be dropped and damaged.
The subject invention overcomes the foregoing shortcomings of the prior art Tekmax plate handling apparatus by providing an apparatus that grips a portion of the stacks of plates that will form a cell and raises them above the paddles of the plate stacking apparatus that transports them. The apparatus then rotates the gripped stacks 180.degree. as a group and grips the remaining stacks from the plate stacking apparatus, with the stacks in the second group being interposed between the stacks in the first group. The apparatus then reduces the separation between the gripped stacks, moves them over the cast on fixture, lowers them into the fixture and releases them.
The gripping head of the apparatus include a pair of opposed cam elements that have separate cam faces for opening and closing. The cam elements are rotatably mounted and are moved between their gripping and release positions by raising and lowering a cam follower, which is interposed between them and is operated by a doubleacting pneumatic actuator. The cam faces that are used to close the fingers are arranged so that the stack of plates is not released upon loss of actuator pressure.
A plurality of gripping heads are slidably mounted in side-by-side pairs on tracks, except that the heads at one end of the apparatus are not slidable. The heads at the opposite end of the apparatus are attached to the piston of a linear actuator that moves them back and forth along the tracks. The gripping heads are connected together by chain links that are sized to prevent them from separating from one another by a distance that is greater than one-half of the distance between the pockets in the stacking apparatus that carries the stacks of plates. Thus, when the actuator piston is extended the heads are evenly spaced at their maximum separation. Bumpers on the gripping heads prevent them from coming closer together than the distance the stacks of plates are separated from one another in the cast on fixture. Thus, when the actuator piston is retracted, the heads are evenly spaced at their minimum separation.
The gripping heads are mounted on a platform that is movable back and forth along a beam that extends over the stacking apparatus and the cast on fixture. The platform also can be raised and lowered and rotated 180.degree..
Accordingly, it is a principal object of the subject invention to provide an apparatus that will lift a group of spaced-apart vertical stacks of plates, reduce the separation between the stacks in the group and deposit the group of stacks at a remote location.
It is a further object of the subject invention to provide such an apparatus which causes a portion of the stacks in the group to be 180.degree. opposed from the remaining stacks when the group is deposited.
It is a still further object of the subject invention to provide such an apparatus wherein the gripping heads used to lift the stacks utilize cam elements that are positively moved between their open and closed positions by linear movement of a cam follower.
It is a yet further object of the subject invention to provide such an apparatus in which the fingers in the gripping head are opened more quickly than they are closed.
It is a further object of the subject invention to provide such an apparatus in which the fingers in the gripping heads will not open if pressure is lost at the actuator that operates the cam follower.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.